Flood Observation Uncertainty

Flood observation uncertainties are crucial data to appreciate the accuracy of flood discharge, extent, and depth observations. Overall, the current global system of observations is not able to properly observe floods spatially and continuously, therefore leading to important uncertainty. Flood observations are then obtained from gauge discharges that can be measured directly or derived from space-borne observations with associated uncertainties that tend to overestimate or underestimate river discharge during floods. Space-borne Optical and Synthetic Aperture Radar (SAR) are modern methods to observe floods over large surfaces, but with uncertainties associated with cloud and backscatter coefficient interpretation. However, it usually achieves an accuracy of flood extent of over 80% when compared to ground observation. Flood depth RMSE reached < 0.5m when LiDAR data were used for the Digital Elevation Model (DEM) combined with flood extent. In this chapter, we gather dispersed information on flood observation uncertainties and discuss recent development and limitation of flood observation uncertainty.